An environmental group seeking more information about dozens of contaminated sites in New Jersey has run up against a brick wall in the form of the Environmental Protection Agency.

The Public Employees for Environmental Responsibility wants to know how dangerous the agency considers some 70 sites, including the former E.I. DuPont De Nemours & Company plant, which made munitions in Pompton Lakes. There are several sites in Mercer and Burlington counties as well.

The group known as PEER filed suit this week in U.S. District Court for the District of Columbia to compel the EPA to release its hazardous ratings system scores for the sites. The ratings, based on factors such as the risk to area residents and groundwater contamination, determine which sites merit immediate attention. Sites with the highest scores qualify as “Superfund” sites, a designation that opens up federal funding for cleanup.

New Jersey already has 144 Superfund sites; more could be added depending on the rankings that the EPA is keeping quiet. The information would enable “apples-to-apples comparisons which, in turn, would help prioritize sites for cleanup and target responsible parties,” according to PEER.

This would seem to be a simple matter with no need for lawsuits. After all, the EPA exists to make sure “all Americans are protected from significant risks to human health and the environment where they live, learn and work.” Providing a clearer picture of the risks through its hazardous rating systems appears to be part of that mission.

Yet the EPA ignored a Freedom of Information Act request submitted by PEER for disclosure of the ratings.

Based on a 1991 memo, EPA officials said the ratings are considered “pre-decisional” policy recommendations and so are exempt from the open records law.

“By failing to disclose these hazardous ratings, EPA keeps the public in the dark about risks in their communities and frustrates their efforts to hold polluters and government accountable,” says New Jersey PEER Director Bill Wolfe.

He’s right. And PEER was right to file the suit since it appears that will be the only way to get the information.

Residents of New Jersey and every other state should have the right to know what is simmering in their own back yards. It is disappointing that the EPA, especially under a president who has promised openness and transparency, should refuse to divulge that information.